waecmaths question:
If 25y = 1111two ,find the value of y
Option A:
4
Option B:
5
Option C:
6
Option D:
7
waecmaths solution:
$\begin{align} & {{25}_{y}}={{1111}_{two}} \\ & 2\times y+5\times {{y}^{0}}=1\times {{2}^{3}}+1\times {{2}^{2}}+1\times {{2}^{1}}+1\times {{2}^{0}} \\ & 2y+5=8+4+2+1 \\ & 2y+5=15 \\ & 2y=10 \\ & y=5 \\\end{align}$
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